“S” cam drum brake squeal in heavy-duty vehicles remains a less explored issue despite advancements in light vehicle brake noise control. This study focuses on key operating parameters, friction coefficient and air chamber pressure that influence squeal in “S” cam drum brakes. Using finite element analysis (FEA) and statistical methods, the research bridges the gap between simulation predictions and real-world performance. Complex eigenvalue analysis (CEA) was used to study to understand eigenvalues and eigenvectors changes with varying air chamber pressure and friction coefficient. This helped identify critical operating parameters causing squeal noise index. Statistical analysis then confirmed the recurrence of unstable modes seen in both FEA and test data. The results provide insights into dynamic instabilities and establish a method for detecting mode coupling issues. Combining FEA and statistical models accurately predicts the critical friction coefficient and air chamber pressure levels for stable brake design. Strong alignment between simulation results and experimental data validated the proposed approach. However, the study has some limitations, including the risk of overpredicting squeal due to missing damping assumptions and extensive simulation runs. The method was validated only for “S” cam drum brakes, though it could be adapted for other any brake systems with further testing. This research stands out by combining CEA and statistical techniques to address brake squeal. It provides a practical and validated approach for early squeal detection and mitigation. The framework also supports parametric optimization, reducing design optimization trial, and also provide effect on optimized on other noise zones as well.